In Agile developments, the scope line of burn-down charts should never go up unless it is a planned (removing other similarly estimated stories, or adding more resources to the team) addition of requirements to the project. If there are estimates that are bad:

1) If the wider project is believed to have incorrect estimates, then, the entire work should be re-planned, otherwise there is a huge delivery risk, i.e. The entire team having to consistently throughout the project work long hours (developer productivity is limited to a few hours a day and it is unlikely 10 hours of pair programming could work), or having unachievable velocity requirements. However, this is a benefit as this is determine within the first 2-3 iterations (hopefully they’re 2 weeks).

2) Scope line should be progressing by increasing the estimates of the stories that have lower estimates (if some estimates were wrong), but at the same time removing “Would haves” or “Could Haves”

3) It should be looked at on what was missed (e.g. consistently leaving out acceptance test scripts) for the stories to be estimated or a ‘Safety Check’ (used in retrospectives) to allow the facilitator to check if the developers will be open and honest about estimates.